Cornelius J.a. Jansen, MD
Otolaryngology Physician · Walnut Creek, CA
Cornelius J.a. Jansen, MD is an otolaryngology physician with a practice address in Walnut Creek, California, and NPI 1285712380, issued on Nov 2, 2006. Check the license (California G85048, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Cornelius J.a. Jansen
- Credential
- MD
- Primary taxonomy
- Otolaryngology Physician 207Y00000X
- License number
- G85048 CA
Self-reported in NPPES; status is on the state search - Practice location
- 1425 S Main St, Walnut Creek, CA 94596
- Phone
- (925) 295-4000
- Enumerated
- Nov 2, 2006
- Record last updated
- Oct 11, 2019 (not updated in 7 years: call before relying on the address or phone)
- Medicaid ID
- 00G850480 CA
- Entity
- Type 1 · individual
8 nearest otolaryngology physician records → All 1,212 in California → Look up another NPI →
Also registered at 1425 S Main St
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Eric AaserudeEmergency Medicine Physician1811491194
- Derek Abbassi, MDObstetrics & Gynecology Physician1841364155
- Peter Ackerman, MDEmergency Medicine Physician1427435023
- Aaron Mark Acosta, DOEmergency Medicine Physician1538789987
- Basil Adad, MDOtolaryngology Physician1487732574
- Derek Ailes, M.D.Emergency Medical Services (Emergency Medicine) Physician1992001804
Verify Cornelius J.a. Jansen in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G85048Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
94% fewer Medicare Part D claims than the average otolaryngology physician in 2024
30 Medicare Part D claims for 17 beneficiaries, against an average of 541 among the 8,339 providers of this specialty who prescribed in Part D.
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Cornelius J.a. Jansen among 1,212 otolaryngology physician records in California
Cornelius J.a. Jansen, MD is one of 1,212 otolaryngology physician records with a practice address in California. 80% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 7% of them.
- NPI issued2006 · 7% of these records are older, 52% newer
- In a Medicare fileYes · 80% of these records are
- In the CMS Doctors and Clinicians fileNo · 67% of these records are
- Record last updated2019 · 63% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207Y00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Otolaryngology Physician providers in California
There are 1,212 otolaryngology physician records in California.
All 1,212 in California → Every provider in Walnut Creek → Otolaryngology Physician nationwide →
The 8 otolaryngology physician records with the nearest ZIP codes
- Basil Adad, MDWalnut Creek, CA 945961487732574
- Gregory Chin, MDWalnut Creek, CA 945961710056924
- Nicole Daamen, MDWalnut Creek, CA 945961093893588
- Bryan Fong, MDWalnut Creek, CA 945961033297163
- Elizabeth Huang, MDWalnut Creek, CA 945961629156781
- Christopher Mascarinas, M.D.Walnut Creek, CA 945961952596744
- Glenn Schneider, MDWalnut Creek, CA 945961033297114
- Betty Tsai Do, MDWalnut Creek, CA 945961629293030
Common questions
What is Cornelius J.a. Jansen, MD's NPI number?
Cornelius J.a. Jansen, MD's National Provider Identifier (NPI) is 1285712380, issued on Nov 2, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Cornelius J.a. Jansen, MD located?
The NPPES record lists a practice address at 1425 S Main St, Walnut Creek, CA, 94596. Phone: (925) 295-4000. Providers update this record themselves, so call before visiting.
How can I verify Cornelius J.a. Jansen, MD's license?
NPPES lists California license number G85048, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Cornelius J.a. Jansen, MD prescribe under Medicare Part D?
In 2024, Cornelius J.a. Jansen, MD had 30 Medicare Part D claims for 17 beneficiaries; the average among otolaryngology physician prescribers was 541. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.